Laravel Error Illuminate\Support\Manager::createDriver()

I just got error in my laravel project, and the error was Illuminate\Support\Manager::createDriver(). I was able to solve this problem, so i want to share it here, in case someone else had the same error.

Laravel 5.5 error No application encryption key has been specified.

This morning when i clone one of repository on my github (this repo is based on laravel 5.5) to another computer, i got an error RuntimeException No application encryption key has been specified. How to solve this problem?